36. The correct answer is D. This is a psychotic level disorder (the patient is hallucinating). The patient has a fluctuating level of consciousness and is disoriented. Also, there is a clear history of a febrile condition that developed rather rapidly, all of which suggest delirium.
In acute stress disorder (choice A) a traumatic event occurs that precipitates an anxiety-type reaction, not a change in the sensorium.
In both bipolar I disorder, manic type (choice B) and brief psychotic disorder (choice C), patients may reach a level of behavioral disruption of psychotic proportion. They do not, however, demonstrate changes in level of consciousness or major disorientation.
Persons with dementia (choice E) demonstrate a clear sensorium with no fluctuations in the level of consciousness. In addition, persons with dementia predominantly show symptoms of impairment of cognitive functions (e.g., memory impairment).